/*
We shall call a fraction that cannot be cancelled down a resilient fraction. Furthermore we shall define the resilience of a denominator, R(d), to be the ratio of its proper fractions that are resilient; for example, R(12) = 4⁄11.

The resilience of a number d &gt; 1 is then
φ(d)d − 1
, where φ is Euler's totient function.

We further define the coresilience of a number n &gt; 1 as C(n)= 
n − φ(n)n − 1.

The coresilience of a prime p is C(p)
= 
1p − 1.

Find the sum of all composite integers 1 &lt; n ≤ 2×1011, for which C(n) is a unit fraction.

Anser:
Time:
*/
package main

import (
	"fmt"
	"time"
)

func main() {
	tstart := time.Now()



	tend := time.Now()
	fmt.Println(tend.Sub(tstart))
}